Disposable absorbent products can be fabricated in a continuous production line by the sequential addition of components to previously supplied components. This is particularly advantageous when one or more of the components can be supplied in the form of a single continuous layer. For example, in the formation of disposable absorbent articles, such as training pants, absorbent pants, diapers, incontinence articles, feminine care products, or the like, a layer is normally supplied at a point in the fabrication line in the form of a continuous roll, and absorbent pads, waist elastic bands, leg elastic bands, stretchable side panels, and/or other components can be supplied at different points in the fabrication line as discrete elements.
Various processes and apparatus are available for bringing the components of a single product together so that the components in the composite product are in a desired relation with respect to each other. In bringing these components properly together, various known processes and apparatus are used to note the position of a particular component, and then to adjust the position of subsequent components in order to properly position them.
A problem encountered with these types of processes and apparatus is that they do not adequately compensate for the stretching, or other possibly occurring defects, of a continuously moving layer. During manufacturing processes of this type, a continuously moving layer is subjected to various tensions caused by it being driven or pulled through the process for handling. This tension causes the continuously moving layer to stretch, or to relax, thereby resulting in some components being undesirably positioned or, once positioned, shifted out of position. Since it is virtually impossible to maintain a constant tension on the continuously moving layer, the degree of stretching varies throughout the process. Consequently, even though an earlier positioned component may initially be within an acceptable position range, the stretching, by way of example, of the continuously moving layer may result in the component being outside of the acceptable position range in the final composite product. Other undesirable occurrences may also result in mis-registration of a component or components.